A luscious broiled sea trout fillet bathes in a broth boosted with glutamic sake lees. Credit: Danielle A. Scruggs

Loyalists were “persons inimical to the liberties of America,” as was said by patriots during the Revolutionary War. On their worst days they were often subject to arson and tarring and feathering, but at war’s end many of them—including former slaves—were granted asylum in Canada.

Maybe chef John Shields and pastry chef Karen Urie Shields chose to name their high-volume hangout below their fine-dining flagship, Smyth, after the king’s men for its subterranean qualities. With its darkened walls barely illuminated by candlelight and a long, glowing bar, it’s the sort of place where counterrevolutionaries might meet to plot over their syllabub. Maybe so, but what the dim room dominated by communal high-tops mostly communicates is a conceptually blank slate.

At a brief glance, the menu doesn’t seem particularly revolutionary either, not in the way you’d expect from vets of Trotter’s, Tru, and Alinea who’ve returned to Chicago after a celebrated stint at their rural Virginia restaurant Town House. It has that familiar something-for-everyone vibe, with the usual heirloom tomatoes, chicken liver mousse, aged rib eye, and, of course, a cheeseburger. But upon closer inspection, something more unexpected is afoot.

There’s a luscious broiled sea trout fillet bathing in a broth boosted with glutamic sake lees (aka sakekasu, the solids left over after sake is separated from fermented rice), enhancing both the fish and the scarfable bits of charred cucumber floating in the brew. There’s a pair of lightly fried boneless chicken thighs flanking a bed of rice grits creamier than any risotto, along with green beans, and bits of toothsome pickled tripe that lend a surprising acidity. And there’s a barbecue plate—a chunk of roasted pork shoulder slathered in an understated sauce, the meat so tender you won’t mind that it’s billed as “BBQ.” Slippery rings of calamari tangle with charred eggplant and fruit bombs of Fresno chiles, while fat, sweet charred carrots are draped with ropes of dueling acidic-creamy salsa verde and bearnaise sauce.

A casual hangout like the Loyalist is legally beholden to have fried potatoes on the menu (there are two versions, in fact); nevertheless its “smokey” potatoes, while not particularly smoky tasting, are a happy surprise, bedded on a fried egg showered with tart sauerkraut, the whole baby spuds’ crispy outer shell jacketing an ethereal interior. That’s not the only apparently boring menu item that turns out to be loaded with culinary purpose. The chicken liver mousse, slathered on toast, has an iron-rich minerality offset by sweet cherry and a blanket of crisp, cool radishes. A panzanella with a gob of fresh cheese and hunks of black-garlic sourdough is summer’s last caress. And that cheeseburger? It has its own Twitter and Instagram accounts attesting to its lacy smashed-patty crackliness and curtains of molten cheese and grilled onions—a sloppy champion of the form.

The standout among a trio of desserts from Urie Shields is a sort of collapsed pavlova—shattered dry meringue concealing smooth blackberry sorbet. But you can’t do much worse with a dense, stygian chocolate layer cake balanced with a dollop of whipped creme fraiche, or a light lemongrass sundae drizzled with salted black-licorice caramel.

The Loyalist has an extensive and approachably priced wine list for a restaurant with such a tight menu—and so too is its cocktail list, ten potions ranging from the boozy straight-up Hemingway Daiquiri to the Tarantella, a chuggably fruity concoction built with pisco and sparkling wine, to the No True Scotsman, with two kinds of scotch and creme de violette.

If this basement barstaurant exists only to help underwrite the significantly more costly prix fixe operation upstairs, it’s doing way more than it needs to. It may be difficult to spot right away, but the Loyalist has an identity all its own.